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A5557 - Predictive Score of Pulmonary Tuberculosis in Both Smear Negative and Culture Negative Bronchial Samples
Author Block: C. Fraisse1, G. Devouassoux2, L. Kiakouama3, F. Ader2, J. Giai1; 1Hospices Civils de Lyon, Lyon, France, 2Hospices Civiles de Lyon Hopital de la Croix Rousse, Lyon, France, 3Hospices Civils de Lyon Hôpital de la Croix Rousse, Lyon, France.
Rationale :
With 10.5 million incident cases worldwide, tuberculosis remains a major public health problem. In France, out of 5000 new cases of pulmonary tuberculosis reported per year, 24% of newly notified pulmonary tuberculosis cases are smear-negative. Waiting for the final results of the culture can last 90 days, in such a situation, a probabilistic antibiochemotherapy may be started.
The aims of this study were to follow-up and determine differential diagnosis in case of final negative culture ; to establish a predictive model of negative long-term culture for Mycobacterium tuberculosis (MT) from bronchial samples, to help treatment decision making.
Methods :
This retrospective study was performed from 2009 to 2016 at Hospices Civils de Lyon and included every patient suspected of smear-negative pulmonary tuberculosis and treated by specific antibiotics. Patients were divided into 2 groups: firstly smear-negative pulmonary tuberculosis with negative culture and secondly smear-negative pulmonary tuberculosis with positive culture. For smear-negative culture-negative patients, final differential diagnosis were checked in the medical records. After multiple logistic regression, a predictive score for positive MT culture was created.
Results :
From 658 hospitalized patients for tuberculosis, 169 were smear-negative and 58 were initially culture or PCR negative for MT. Finally, cultures remained negative for 39 patients and became positive for 19. A differential diagnosis was done in 17/39 patients :7 non-infectious granulomatosis including 5 sarcoidosis; 3 inflammatory / autoimmune diseases, 1 langerhans cell histiocytosis, 2 cancers, 1 non-tuberculous mycobacterial disease and 3 pleuritis. In multivariate analysis, a late positive culture for MT was significantly associated with an involvement of pulmonary upper lobes (OR = 11.28 [1.88-107.40], p = 0.0172), the absence of lesion in the middle lobe (OR = 5.83 [1.15-37.94], p = 0.0439). A low BMI was also significantly associated with late MT positive-culture (OR = 0.82 [0.67-0.97], p = 0.0389).We established a predictive score of late MT positive culture, based on computed tomography characteristics and BMI, with an AUC at 0.83 (95% CI [0.72-0.93]) on ROC curve.
Conclusion :
The management of smear-negative pulmonary tuberculosis remains challenging and the decision to initiate a specific treatment is still largely debated . Our study demonstrated that a majority of such cases remained without bacterial demonstration for MT, leading to consider alternative diagnosis. We propose an original predictive score for late positive MT culture. This score requires to be further validated, but may constitute a valuable tool for early therapeutic decision.